Determine the dose-response curves for the production of mouse skin tumors by ultraviolet light of wavelengths 254 and 290-320 nm. Determine the co-carcinogenicity of optical brighteners given in conjunction with various wavelengths of ultraviolet light, and by modes of application agreed upon by the Contractor and the Project Officer. Fractionate condensed coal tar and test carcinogenicity by skin application to mice and by inhalation of respirable coal particles in hamsters. Initiate such related or alternative investigations of other environmental compounds or treatments as may be required and approved by the Project Officer.